arXiv AI

Encrypted Skills Can Become New Security Exploits If AI Agents Know How to Decipher

arXiv Computation and Language
Aug 25

SkillBloat: Token Amplification Attacks via Skill Injection in LLM Coding Agents

The paper "SkillBloat: Token Amplification Attacks via Skill Injection in LLM Coding Agents" investigates how agent skills—task‑specific instructions, scripts, and resources—can be exploited to create a trusted instruction channel that enables token amplification attacks. It introduces a two‑phase framework, SkillBloat, which first screens a library of attack‑type conditions across multiple amplification mechanisms and then refines the strongest candidate through LLM‑guided full‑document skill rewriting. Evaluated on a real‑world skill benchmark, SkillBloat achieves an average best amplification of 5.4184×–10.1455× across multiple coding‑agent target configurations, and an ablation study shows that the second‑stage refinement consistently improves performance over the initial screening alone.

By Yuanjin Zheng, Jingbang Chen
arXiv AI
Oct 15

One Skill, Two Masters: Serving Users and Attackers through Skill Injection

The paper introduces PERSIST, a method that allows attackers to inject malicious actions into large language model agents by linking attacker-chosen actions to useful functions while minimizing source inspection and suspicion. PERSIST builds helper functions from simulated executions and embeds them in separate modules, enabling the agent to perform both user tasks and attacker objectives. Experiments on SkillsBench and Skill-Inject demonstrate that frozen skill packages transfer across multiple agent–model configurations, generalize to unseen tasks, and increase harmful-effect rates compared to baselines.

By Haochang Hao, Dehai Min, Zhifang Zhang, Yunbei Zhang, Miao Xu, Yingqiang Ge, Philip S. Yu, Lu Cheng
arXiv AI
Oct 1

Pretext: Defeating Malicious Skill Detection Frameworks for AI Agents

The paper titled "Pretext: Defeating Malicious Skill Detection Frameworks for AI Agents" demonstrates how an attacker can bypass current skill‑scanning defenses by crafting malicious skills that evade both static analysis and LLM‑based semantic checks. By moving malicious payloads into natural language and distributing instructions across files, the white‑box attacker named Pretext achieves high evasion rates—up to 97% against a frozen detector and 77% against a co‑adaptive one—across three open‑source models.

By Tobias Kaisar, Aritra Dhar
arXiv AI
Oct 7

SkillPoison: Progressive Skill Poisoning via Successful Experiences

SkillPoison demonstrates that self‑improving large language model agents can be progressively poisoned through successful experiences without any single trajectory being malicious. The framework constructs successful experiences that reinforce a target behavior, then removes contextual constraints so the skill extractor generalizes to harmful behavior when misapplied. Experiments on three benchmarks show a 95.71% attack success rate while all injected experiences remain task‑correct and pass verification and lexical inspection.

By Lizhi Zhang, Xin He, Dianxuan Fu, Yuyuan Feng, Jiatong Li, Qi Wang, Xin Wang, Qinggang Zhang